1. Field of the Invention
The present invention generally relates to a semiconductor device and a method of forming the same.
Priority is claimed on Japanese Patent Application No. 2011-33431, filed Feb. 18, 2011, the content of which is incorporated herein by reference.
2. Description of the Related Art
With an increase in the level of integration and the functionality of semiconductor devices in recent years, the interconnection pitch has been further reduced, and the need for reduction in size has been increasing. Accompanying this, problems, which need to be overcome, have occurred.
For example, in a DRAM (dynamic random-access memory), which is one example of a semiconductor device, with a reduction in the interconnection pitch, there has been a reduction in the contact surface area between an active region and a bit line contact in a memory cell, this being accompanied the problem of an increase in the contact resistance.
Japanese Patent Application Publication No. JPA 2010-147078 discloses that in a constitution of an active region that extends in a direction that intersects with bit lines and word lines. There is a prominent reduction in the contact surface area between the active region and the bit line contact.
Japanese Patent Application Publication No. JPA 2000-307084 discloses a method that, in a constitution in which an active region extends in a direction that is parallel to a bit line, forms the active region into a T shape and causes the upper surface of the protruding part of the T to contact with the bit line contact, so as to increase the contact surface area between the active region or an impurity diffusion region and a bit line contact, thereby reducing the contact resistance.
Even the direction of extension of the active region is parallel to the bit line. The protruding part of the active region is formed in a T shape. Thus, it was difficult to achieve a sufficiently high level of DRAM integration.